Cellulose film and foil and method of making the same



UNITED ST'iEfi CELLULOSE FILM AND FOIL AND METHOD OF MAKING THE SAME George Schneider, Montclair, N. 5., assignor to Celanese Corporation of America, a corporation of Delaware No Drawing. Application November 1, 1934, Serial No. 751,034

3 Claims. (Cl. 18-57) This invention relates to artificial materials, and a solvent, such as glacial acetic acid, for the such as sheetings, films, foils, etc. that may be ester as it is formed. After esterification, as is translucent, opaque and more especially transusual in the production of yarns, films, etc., the parent, the base material of which is a product of cellulose ester may be allowed to stand containing 5 thecomplete or partial de-esterification or saponiat least a part of the catalyst to hydrolyze or 5 fication of a cellulose ester and more particularly ripen to a product of the desired acyl value and an organic ester of cellulose such as cellulose solubility characteristics, after which the cataacetate. lyst may be neutralized and the ester precipitated An object of the invention is the economic and and stabilized. l0 expeditious production of shootings, films, foils Other methods of forming the cellulose ester and other artificial materials containing the may be employed. In forming articles according product of the saponification of organic esters of to this invention, however, the ripening and stacellulose. Other objects of the invention will apbilizing steps may be dispensed with and the pear from the following detailed description of films, foils, etc. formed direct from the esterifying the invention. mixture or from the re-dissolved ester precipi- 15 By this invention artificial materials especially tated directly after completion of esterifioation. films and foils may be formed by a direct method In eliminating the ripening and stabilization and without expensive chemical recovery systems steps, the method comprises the production of and/or loss of chemicals. The product produced a cellulosic sheet, film, etc. in the most direct is of excellent clearness and strength. fashion conceivable. Thus, a continuous film or 20 By the method of preparation according to this foil may be formed by the precipitation or Wet invention, many effects may be obtained in the method from the primary acetylation mass difinal product that heretofore have not been pracrectly after the acetylation becomes complete and ticable in similar articles of regenerated cellulose. before any water is added as is customary when Thus, a new group of compounds may be incorripening and hydrolyzing. The wet continuous 25 porated in the material as efiect materials that film or foil may then be completely or partially heretofore were prohibited by the solvents and/ or saponified with alkaline or ammoniacal agents,

liquefying chemicals employed in forming regenor even by acid hydrolysis, thus producing a sheet erated cellulose. material that is tough and durable and which According to my invention I form sheetings, may be further processed in the same fashion 30 films, foils and other artificial materials by shapas sheets formed of regenerated cellulose by the ing a solution of an organic ester of cellulose, viscose method. They may be dried, treated with removing the solvent and saponifying the resultglycerine and/or coated with wax, etc. for moisant product. In this manner various eliect mature-proofness.

terials may be incorporated in the article and the In carrying out my invention, any suitable so 35 saponification or regeneration of the cellulose lution of an ester of cellulose, and more particumay be carried to any desired extent with the larly an organic ester of cellulose, is formed into a result that articles having a variety of properties sheet, film or foil in any suitable manner and may be formed. In the description and claims, after formation de-esterified either totally or par the term sheet-like material or article is to be tially to form a type of film containing cellulose 40 understood to mean sheetings, films, foils and or a cellulose ester of relatively low acetyl value. other like materials. Thus, the solution of organic esters of cellulose Any of the organic esters of cellulose are apas it is formed or a solution made by dissolving a plicable to this invention, for example, cellulose precipitated organic ester of cellulose in a suitacetate, cellulose formate, cellulose prcpicnate able solvent may be cast into a film or foil or 45 and cellulose butyrate. Although any of the orextruded through suitable orifices into a solvent ganic esters of cellulose may be empioyed in this removing medium to form a film or foil. The invention, the invention will be described with film o-r foil may be further processed to complete particular reference to cellulose acetate. or substantially complete removal of volatile sol- The cellulose ester may be formed by esterifying vents. 50 with an anhydrous organic acid a natural cellu- These films and foils may contain effect matelose or cellulose pretreated with organic or inorrials for lending color, hand, opacity and other ganic acids. Thus cellulose acetate may be prodesired effects. Examples of such effect mateduced by treating cellulose with acetic anhydride rials are dyes or lakes, pigments, filling material,

in the presence of a catalyst, say sulphuric acid, sizes, lubricants, moisture-proofing material, etc. 5

Many materials may be incorporated into the films or foils by this invention that were not possible by prior methods. Many efiect materials may be employed that are unaifected by the solvent employed in forming the solution of the organic ester of cellulose but which were affected by the so-called solvents for cellulose. Further, a larger variety of solvents may be employed in forming fi ms and foils of organic esters of cellulose than when dissolving cellulose. Examples of efiect materials are powdered metal, oxides of metals, phosphates and silicates of metals or other salts of metals, starch, cellulose or degradation products of cellulose, lamp black, logwood, or other colored pigments, and dyes, tricresyl phosphate, or other alkyl or aryl phosphates, glycerine glycols or their derivatives or substitution products etc.

The efiect materials may be incorporated with the films or foils by adding same to the solution from which the films or foils are formed. The solvent for the organic ester of cellulose should be selected that will have little or no undesired effect upon the effect material yet has a good solvent action on the particular organic ester of cellulose employed.

Any suitable solvent for the organic ester of cellulose may be employed, for forming the solution from which the films are formed. Examples of such solvents are, acetone, mixtures of acetone, and methyl or ethyl alcohol, chloroform, ethylene dichloride, mixtures of ethylene dichloride and ethyl or methyl alcohol, methyl chlo ride and ethyl or methyl alcohol, etc. or mixturcs of these. The organic esters of cellulose may be dissolved in the solvent in amounts of from 5 to 40 parts to 100 parts of solvent and the effect material added to the solution if same be used. This solution may then be shaped and the solvent at least partially removed.

After the sheet-like article, say foil or sheets of from 1/1000 to 15/1000 inch in thickness or other articles, are formed the same may be treated in a warm bath containing sodium, potassium or ammonium hydroxide for a period of time to either partially or completely saponify the material, or the material may be subjected to the vapors of ammonia or the material may be saponificd by an acid hydrolysis method. Thus, any suitable method of saponification may be employed to form the altered cellulose ester or cellulose film, foil, sheet, etc. For examples there may be used the methods and/or reagents described in U. 5. Patents Nos. 1,425,364, 1,442,631, 1,802,956, 1,818,466, 1,866,153, 1,884,622, 1,884,623, 1,895,919, 1,897,691 and U. S. applications Nos. 655,778 filed Feb. 8, 1933; 668,070 filed April 26, 1933; 709,334 filed Feb. 1, 1934; 709,335 filed Feb. 1, 1934; 709,336 filed Feb. 1, 1934; 525,612 filed March 26, 1931; 629,906 filed Aug. 22, 1932, 655,773 filed Feb. 8, 1933 and 655,774 filed Feb. 8, 1933. Although these patents and applications are primarily directed to the treatment of filaments, yarns and/or textile fabrics, the adaptation of their process and reagents to the treatment of other articles is obvious.

In one form of my invention a film of organic ester of cellulose is cast upon a film forming wheel that dips into a trough containing a saponifying agent in such a manner that the film contacts with the saponifying agent prior to removal of film from the surface upon which it is cast and in some instances prior to complete removal of the solvent of the solution from which it was cast.

By the wet method, films or foils may be extruded through suitable orifices or cast upon a suitable surface directly into a mixture of a solvent removal or precipitating agent and a saponifying agent.

As an illustration and not as a limitation the following example is given.

Example The free sulphuric acid present in an unprecipitated unripened esterification charge of cellulose acetate is neutralized by the addition thereto of dry sodium acetate. The viscosity of the solution is lowered by the addition of acetone, say 100 parts of acetone to 100 parts of the primary acetylation solution that contains cellulose acetate dissolved in acetic acid. Films of about 2/1000 inch thickness are cast on a smooth surface and immediately immersed in a bath containing sodium hydroxide in 90% ethyl alcohol for from 1 to 10 minutes. The time of saponification may be shortened by increasing the temperature of the bath, the concentration of the alkali and/or by the use of electrolytes. After air drying, the films are stripped from the surface upon which they were cast. This procedure results in a film of exceeding clearness and with a smooth surface. The film is pliable and possesses considerable tensile strength. Although in this example the film is not completely saponified, it nevertheless may be dyed with cotton dyes. For complete saponification resulting in a film of similar physical properties, the length of treatment in the saponifying bath may be from 4 to 30 minutes.

It is to be understood that the foregoing detailed description is merely given by way of illustration and many alterations may be made therein without departing from the spirit of my invention.

Having described my invention, what I desire to secure by Letters Patent is:

1. Process for the manufacture of sheet-like material containing cellulose, which comprises forming a mixture of an effect material and a primary solution of cellulose acetate, forming a sheet from said mixture, and treating the formed sheet with an alcoholic alkali solution to effect complete saponifica-tion of the cellulose acetate to cellulose, whereby a sheet-like material 0011- taining cellulose and having the effect material dispersed throughout the same is formed.

2. Process for the manufacture of sheet-like material, which comprises forming a mixture of cellulosic eifect material and a solution of cellulose acetate, forming a sheet from said mixture, and treating the formed sheet with a saponifying agent to effect complete saponification of the cellulose acetate to cellulose, whereby a sheet-lil ze material containing cellulose and having the effect material dispersed same is formed.

3. Process for the manufacture of sheet-like material, which comprises forming a mixture of an effect material and a solution of cellulose ace tate, forming a sheet from said mixture, and treating the formed sheet with a saponifying agent to effect complete saponification of the cellulose acetate to cellulose, whereby a sheetlike material containing cellulose and having the effect material dispersed throughout the same is formed.

throughout the GEORGE SCHNEIDER. 

